Formation of zeolite films and their properties

FORMATION OF ZEOLITE FILMS AND THEIR PROPERTIES SUMMARY Keywords: Zeolite micropattern, self-assembly, thin film coating, colloid, nanoparticle. Zeolites are crystalline porous solids with molecular-sized voids and channel systems. They are widely used in oil refining and petrochemistry as solid acid catalysts. Considerable efforts have been directed toward the preparation of zeolite thin films because of their potential application as membranes, membrane reactors, heat pumps, catalytic coating reactors, chemical sensors and components in microelectronic devices. Most of the zeolite films available today are randomly oriented even though a preferred orientation is often desirable. Recently, oriented continuous zeolite A films were successfully prepared on ceramic substrate with seeded-growth method in which a zeolite seed layer is deposited on the substrate prior to a hydrothermal treatment. In this study, a novel type of self-assembly technique was developed for the preparation of micropattern zeolite films. Poly(dimethylsiloxane) stabilized colloids of zeolite and aluminum nanoparticles were prepared in acetone. Zeolite nanocrystals were self-assembled as organized micro patterns on various solid substrates during solvent evaporation. Circle shape wire patterns with uniform radius were built inside capillary substrates, glass vials and beakers. Two-dimensional microchannels and complex micropatterns can be easily fabricated on solid substrates using this self- assembly technique. This procedure replaces the multiple stages of photolithography and pattern registration involved in photolithographic fabrication. The method is also applicable to the patterning of metals, organic polymers, inorganic crystals, and ceramics on the inner walls of preformed capillaries. Faster production of zeolite micropatterns was also achieved by using microwave heating or by moving the colloid solutions. The assembly of colloidal particles holds promise for the miniaturization of many devices. xv